Automatic fire alarm



July 14, 1931. H. CQOSBORN ,y l l1,814,733

AAUTOMATIG `FIRE ALARM Filed Jan; 24, 1931 A Patented July 14, 1931 HAROLD C. OSBOBN, F PALATNE, ILLINOIS 'Avremmo FIRE' man .sppnoacmn med yJanuary a4, 1931. serial No'. 510,953.

This invention relates to automatic lire alarms, and its principal object is to provide an alarm adapted to be set into operation under an increase in temperature consider- @ably above the normal temperature ofthe place where the alarm is located. Another object is to provide an automatic fire alarm composed entirel of mechanical elements and self-centaine as a compact unit, whereby it may be placed in any convenient point 'in a dwelling or other building.

Sometimes a fire breaks out in a building and the persons therein `are unaware of the tire until it has made sufficient headway to endanger the entire building, as well as the 'lives of the occupants, and anY object of this invention is' to provide a simple and highly ecient mechanical alarm mechanism which is. sensitive to an increase in temperature substantially above the normal temperature in the place in which the alarm is located. Another object is to rovide a fire alarm having an alarm sounding device which shall produce a relativel vhigh and shrill sound which is readily istinguishable as a fire alarm and capable of being -heard at a considerable distance away from the place Where the alarm is installed.

With these and other objects and advantagesin view this invention consists in a fire alarm embodying a spring motor having means controlled by thermostatic chan es adaptedto actuate an alarm sounding device. It further consists in` a fire alarm embodying a spring motor having means for actuatlngthe alarm sounding device and provided with a thermostatic arm acting to prevent operation of the spring motor under normal thermal conditions.

llt further consists in the several novel features hereinafter set forth and claimed.

The invention is clearly illustrated in the drawings accompanying this specification in whichn Figure l is a front elevation, partly in vertical longitudinal section, of an automatic fire alarm illustrating one embodiment of the present invention; and

Fi 2 is a vertical cross section taken on the line 2 2 of Fig. 1.

'9 of the spring Referring to said drawing, the reference character 3 designates a case or cabinet, the' walls of which are preferably formed of o en work or perforated material. As

.s own, the case is rectangular in form and .je

its four Walls, and top and bottom, are providedwith perforations. The alarm mechamsm 1s ,contained inthe case and, as shown, comprlses, among other thin s, a spring motor 4 mounted upon the bac wall 5 of the tu case. lThe spring motor may be `of any desirable form havmg the` usual spiral spring 6, one end of which is secured to the winding arbor 7 and the other end to a drum connected with a gear wheel 8 which is the `t5 rst of a train of speed increasing gears carried by arbors journaled in the side plates 9 of the spring motor.

Mounted upon the arbor 10 of the last member of the train of gears is a rotatable Yo member, which may be regarded as one element of the train of gears and here shown in the form of a toothed wheel l1, with which engages a thermostatic arm 12, here shown as supported by one of the side plates motor. As is well known, the thermostatle arm 12 is composed of two metals having different A(zo-efficients of expansion, and, as shown, is of curved form, whereby when subjected to an increase in A temperature, the arm tends to straighten and moves out of engagement with the toothed wheel 11. The arniinay'take the form of a detent, its curved end 13 engaging with a tooth of the toothed Wheel 1l, and its other end being curved upon itself, as shown at 14, and secured to a bracket arm 15 screwed or otherwise fastened to one of the side plates 9 of the spring motor. I U nder normal thermal conditions, the free end of the therinostatic arm 12 is held in engagement with one of the teeth of the toothed wheel 11, thereby preventing the spiral spring from unwinding and operating the train of gears. Under an abnormal increase in temperature, however, the thermostatic arm 12 tends to straighten, thereby releasing the toothed wheel 11 and permitting the spiral spring to operate the train of gears of the sprmg motor.

Supported Within the case, as, for in-I ltory tongue 18 on its outer side that engages with the teeth of a toothed wheel 19 which may be one of the gear Wheels of the train of gears oi' the spring motor. llfhenever the toothed wheel 19 is rotated rapidly, it acts on the tongue with a wiping action and as a result the tongue 18, and consequently the diaphragm 17 is vibrated, thereby producing a very shrill piercing sound which is audible at a considerable distance away from the place where the alarm is located.

The thermostatic arm is adjusted to remain inactive under normal thermal conditions, and for an ordinary dwelling or other building is adjustedto remain in engagement with the toothed wheel 11 so long as the temperature at the alarm device remains below 110 Fr., or thereabouts. ln certainl situations, this may be altered, so that the thermostatic arm remains inactive until the temperature reaches a point considerably above 110 Fr.

In the operation of the device, the alarm is placed upon a suitable support, or is suspended from a wall or other part of a room in the building, and the spring is wound up, so that the spring motor will be ready for operation in case the toothed wheel 11 becomes free to rotate. In case a lire breaks out, as soon as the temperature of the room wherein the fire alarm is contained reaches 110 Fr., the thermostatic arm has straightened out suiiciently to become disengaged from .thetoothed Wheel 11, thereby permitting the entire train of gears to r0- tate. As a result, the toothed wheel 19 vibrates thetonguc 18 and diaphragm 17 very rapidly, thereby producing a` shrill vpiercing sound which is audible at a considerable distance away from the place where the alarm is. located, and the attention of persons is thereby attracted to the place where the ire is located.

More or less variation of the exact de 'tails of construction is possible without departing from the spirit of this invention. I desire, therefore, not to limit myself to the exact form of the yconstruction shown and described, but intend, in the following` claims .to point out all of the invention disclosed herein. f

I claim as new, anddesire to secure by LettersPatent: i Y 1. An automatic fire alarm comprising in combination an alarm sounding device including a` spring motor having a train of speed increasing gears, and a thermostatic element anchored at. one end, its other end engaging the last element Vof the train of cluding gears and normally the spring motor vun er norma thermal conditions. l

2. An automatic fire alarm comprising in combination an alarm soundingdevice ina spring motor havin a train of speed increasing gears, one of t e last gears of said train (zo-operating with the a arm sounding device to sound an alarm, and a thermostatic arm normally engaging an element of said spring motorto prevent operation thereof under normal thermal condi*1 tions.

3. An automatic fire alarm com rising in combination an alarm sounding evice including a spring motor having a train of speed increasing gears, and a thermostatic arm normally acting as a detent engaging one of the elements of said train of gears to prevent rotation thereof under normal ther- Amal conditions.

(preventin operation of phragm adapted to be vibrated by one of the last gears of the train. y

5. An automatic lire alarm comprising in combinationia spring motor having a train of speed increasing gears, a thermostatic arm normally engaging a rotatable member Iof the spring motor and serving to prevent rotation thereof under normalthermal con- 190 v ditions and an alarm .sounding .device having a diaphragm adapted to be vibrated by said one of the last. ears of said train.

.6. An automatic re alarm comprising in combination a spring motor having a train of gears and a toothed wheel driven by the last element of the train of gears, a thermostatic arm engaging said toothed wheel and serving to prevent rotation thereof under normal thermal conditions, and a sound amplifier having a dia hragm adapted to be vibrated by one of t e last gears of said train.

7. An' automatic fire alarm comprising in combination a spring tatable high speed toothed diaphragmac tuating member, a thermostatic arm normally engaging one of the rotatable members of said s ring motor, and a. sound amplimotor havlng a ro- ,115

fier inclu ing a diaphragm having a vibratory tongue rojecting therefrom and engaging w1th t e teeth of said diaphragm-ac- .'tuating member, the teeth of said member on the tongue with-.a wiping action.

combination a. spring lmotor having a train of gears, a thermostatiearm acting to prevent o eration of said. sprngmotor under norma thermal onditi'o'ns,='and a sound amacting 8. n automatic'fire .alarm'comprising in 125 pler including'a diaphragm having a vi- 130 bratory tonglue projecting therefrom and engaging wit the teeth of one of the last gears of said train of gears, the teeth of said tongue engaging gear acting thereon with a. `wip1n action.4

9. n automatic fire alarm comprising in combination a spring motor having a train of gears, a toothed member driven by the last element of the train of gears, a thermostatic arm serving as a detent engaging said toothed member under normal thermal conditions, and an amplifier including a diaphragm having a vibratory tongue engaging with one of the last gears of the tram of gears, the 'teeth of said gear acting thereon with a wipin action.

. HA GLD C. OSBORN. 

